Process of continuous two-phase chlorination.



H. T. BOYD.

PROCESS OF CONTINUOUS TWO-PHASE CHLORINATION.

APPLICIITION FILED JAN. 21. I9I8- 1,293,012. Patented Feb. 4, 1919.

Z SHEETSSHEET I- APPLICATION FILED JAN- 21. I918.

Patented Feb. 4, 1919.

2 SHEETS-SHEET 2- anwnl oi UNITED STATES PATENT onnron.

HUGH T. BOYD, OF HOMER, OHIO, ASSIGNOR TO THE OHIO FUEL SUPPLY COMPANY, OF PITTSBURGH, PENNSYLVANIA, A COItPORATION 0F OPHO.

Specification of Letters Patent.

Patented Feb. 4, 1919.

Application filed January 21. 1918. Serial No. 218,089.

To all fwhom it may concern:

" Be it known that I, HUGH T. Born, a citizen of the United States,'residing at Homer, Ohio, have invented certain new and useful Improvements in Processes of Continuous Two-Phase Chlorination, of which the following is a specification.

This invention relates to improvements in processes of chlorinating paraflin hydrocarbons, and relates more particularly to the chlorination of the lower boiling members of the paraffin hydrocarbons in two phases, liquid and vapor, and continuously and its object isto increase the yield of mono-chlorcompounds. By lower boiling members of the parafiin hydrocarbons is meant any of the first eight members of the paraflin hydrocarbon series having more than one carbon atom and hereinafter referred to as lower boiling members of the paraifin hydrocarbons. Each of the improvements composing the invention is intended to be secured for all the usesto which it can be applied, with or without modifications.

In the prior current practice it has been the rule 'to chlorinate these lower boiling members of the paraflin hydrocarbons in either the liquid phase alone by some such method as that of Brooks, U. S. Patent No. 1,191,916 or in the vapor phase alone by a method such as is patented by Graul and Hanschke U. S. Patent 1,032,822

It is known that whether the chlorination of the lower boiling members of the paraflin hydrocarbons is carried on in either the liquid or vapor phase that the saturation of the mono-chlor-compounds in the liquid or vapor cannot be allowed to exceed 20-30%.

- If the saturation exceeds this percentage, the

addition of more chlorin to the system leads to the formation of di- (or) tri-chlor-compounds due to the action of the chlorin on the mono-chlor-compounds. Consequently as soon as the saturation equals the per cent. before mentioned, it is necessary thatp-art of the saturated liquid be led to a still, where the hydrocarbon and chlorhydrocarbon are separated by distillation and at the same time unchlorinated liquid or vapors must -be added to the reaction zone to replace the saturated liquid or vapor withdrawn, thus lowering the saturation per cent. so that the reaction can proceed without undue formation of di- (or) tri-chlor-compounds.

.The number of distillations required in the complete conversion of a given volume of lower, boiling hydrocarbons to monochlor-compounds.results in large, losses by volatilization of the lower boilin parafiin hydrocarbons, no matter how eificlentlythe condensation is attempted.

I have found that in either liquid or vapor phase chlorination there is considerable chlorin carried through unaffected which dissolves in the hydrochloric acid solution, lowering its value commercially. I have also found, in experimenting with liquid phase chlorination devices that the vapors carried from the reaction zone consist almost entirely of unconverted parafiin hydrocarbons, hydrochloric acid and chlorin. For instance, the condensed oil vapors carried from the reaction chamber in chlorinating pentane under the influence of actinic rays, showed on distillation test 96% distilling between 27-40 C.'; a chlorid determination by Rosanolfs method (see Jom'. Am. 071cm. 800., Mar. 1916), less than 1%, a gravity determination of 0.6246 at F. In other words the vapors carried from a liquid phase reaction zone by the hydrochloric acid gas and chlorin contain a negligible percentage of chlor-hydrocarbons.

Now, I have found that by first subjecting the paraifin hydrocarbon in the liquid phase to the action of chlorin and reacting the escaping vapors, which, as we have said, contain practically no chlor-compounds, with chlorin in a separate chamber and in the vapor phase, leading the vapors from the vapor phase chlorination unit to a condenser,

leading the condensate to a still and the uncondensed vapors to a hydrochloric acid any hydrocarbonv scrubber. tank, conductin Vapors from the hydroch oric acid scrubber to other vapor phase chlorination units and repeating continuously that the losses by volatilization are decreased to a minimum, no particular care need be taken of the efficiency of condensation and due to the factthat losses by volatilization are decreased, a higher yield of mono-chlor-compounds per unit volume of hydrocarbon is obtainable.

I have also found that by cutting-down the volume of chlorin in the last tube of the vapor phase units, that practically all the chlorin reacts and almost none escapes to contaminate the hydrochloric acid solution. I

I have found that this system can be operated successfully either under atmospheric,

reduced or increased pressure, increased pressure tending to speed up the reaction.

And, provided the saturation of mono-chlorcompounds is not allowed to become greater at any time than about 25%, in either the liquid or vapor phase tube, the formation of dior tri-chlor-compounds can be held at a minimum. The operator can regulate this s. turation by the rate of, (1) chlorin feed; (2) rate at which fresh pentane is fed to the system; (3) rate at Which the saturated products are fed to the still.

Apparently, although the reaction takes place more slowly, this type of apparatus can be operated in the dark or ordinary daylight. Sunlight or the action of actinic rays hasten the reaction.

The apparatus I have invented for carrying out the idea of two-phase chlorination has for its object not only the securing of an efiicient two-phase chlorination apparatus but a chlorination apparatus whereby more intimate Contact of chlorin with hydrocarbon can be attained than can be secured with thevapor or liquid in one reaction chamber provided with a stirrer or other mechanical agitation device. By means of this apparatus, with the quartz or other glass transparent-to the ultraviolet ray located on each end of each tube, the hydrocarbon in either liquid or vapor phase, saturated with chlorin -comes in contact with the ultraviolet ray in several different zones, being thoroughly agitated before each.

The invention is illustrated in the accompanying drawing'in whieh.

Figure 1 is a view of a liquid phase chlorination unit, showing connections whereby it can be converted to a vapor phase unit, constructed in accordance with the invention.

Fig. 2 shows the method of setting the glass window in each end of each tube. By means of these windows the light rays are transmitted into the interior-of each tube.

'Fig, 3 is a cross sectional View showing arrangement in each tube, of the chlorin inlet. This circular pipe closed at the end is perforated on top. Fig. 4 is a view of a sysgem employing a plurality of units such as 1, 2 and 3 are tubes of any convenient size or shape spaced a sufficient distance apart by means of bolts 4 to allow introduction of light rays between and at the end of each tube. 5 and 6 are pipes connecting each tube to allow liquid or vapor hydrocarbons and chlorin to pass from one tube to the next.

7 shows the spiral deflector set in pipes 5 and 6 connecting each tube. These spirals assist in mixing the liquid or vapor hydrocarbons and chlorin as they pass from one tube to the next.

8 shows inlet liquid hydrocarbon line with elbow at 19 turned down. If the unit is for vapor phase chlorination this line is .closed off. 9 shows the point where vapor hydrocarbons are introduced 'if the unit is to be used for vapor' phase chlorination.

10 shows the point where connection is.

made by pipe similar to 5 to a vapor phase unit similar to Fig. 1.

11 shows the point where vapor connection is made to condenser from the vapor phase chlorination units.

12, 13 and 14 are gage glasses on each tube.

15 shows the chlorin inlets to each tube.

16 shows valves to regulate chlorin feed.

17 shows orifice plates to measure the volume of chlorin.

18 is an outlet for the mixture of hydrocarbons and chlorhydro arbons to the still.

In accordance with the invention, the following features are employed. First, the unchlorinated liquid pentane inlet 8, is near the top of the tube 1" through which the pentane or other paraffin hydrocarbon is pumped into the unit. The liquid hydrocarbon meets chlorin coming through line 15 past valve 16 and measured by orifice plates 17 and is exposed to ultraviolet rays generated in lights 49 at top and bottom of tube 1 supplied from line 4!). From tube 1 on the opposite side from pentane inlet 1 a pipe 6 containing a spiral deflector as a mixer leads to top of tube 2".

Here again the liquid hydrocarbon-chlorin solution after thoroughly mixing around the spiral deflector again enters the ultraviolet ray zone. Chlorin is fed continuously into tube 2" through pipe 15 also near the bottom of this tube, and the ultraviolet ray from 49 again speeds up the reaction. Near the bottom of tube 2 and onthe opposite side from pipe 6" a pipe 5, similar to- 6, leads to the top of tube 3". Here we have again two ultraviolet ray reaction zones, and a bottom chlorin inlet.

Near the bottom of 3 the liquid product. a mixture of hydrocarbon and chlorhydrocarbon is led, through pipe by steam pump 39 or by-pass 43, through line 50 to still 24 where separation is effected by steam distillation.

The vapors from this liquid phase chlorination unit, which consists of tubes 1, 2 and 3 are led from tube 1 through pipe 111 to tube 3*, from tube 3 through pipe 6 to tube 2", from 2 through 6* to tube 1. The arrangement of the ultraviolet ray and chlorin inlets is the same in this vapor phase chlorination unit consisting of tubes 1. 2 and 3 as in the liquid phase unit consisting of tubes 1", 2 and 3". Frorn near the top of tube 1*, a vapor line 116 leads to condenser 117 past sight glass 118 to receiver 119. Any condensate in 119 is led to still 24 through pipe 22. The hydrochloric acid vapors are carried from 119 through pipe 20 which is carried to near the bottom of scrubber tank 21 containing water to absorb the hydrochloric acid. 'If any hydrocarbon vapors come ofi through vent 53 this pipe should be connected to vapor pipe 30 from receiver 27 which leads to a vapor phase chlorination unit.

Still 24 is used to fractionate the hydrocarbon from chlorhydnocarbon. This still does not necessarily have to be of the design shown. Any still with eificient fractionation can be used. The chlorhydrocarbons which we leave in still 24 as residue are pumped from the outlet 42 through steam pump 41 to a washer of any convenient type where the product is neutralized. The unchlorinated hydrocarbon is distilled through column 51, vapor pipe 52 to condenser 25 past sight glass 25 to receiver 27. From receiver 27 the unchlorinated liquid hydrocarbon is led through pipe 28 by pump 40 back through line 29 to the pentane storage to again enter the system through inlet pipe 8.

Any uncondensed hydrocarbon vapors from receiver 27 are led by pipe 30 to a vapor phase chlorination unit which consists of tubes 1, 2, 3, identical with those heretofore described.

Any chlorcompounds condensing in 1 are led to still 24 through pipe 31. From 3 a vapor. pipe 32 leads to condenser 33. Any condensate goes through sight glass 34 to receiver 35 and is led back to still 24through pipe 38. The hydrochloric acidvapors are led from 35 to hydrochloric acid scrubber 37 through line 36. Any hydrocarbon vapors from 37 should be led through vent 54 to the next vapor phase chlorination unit.

The invention lies specifically in the discovery that the vapors from chlorinating liquid pentane contain no chlorpentane or at most only traces. It is known that only a certain saturation per cent. of the chlorinated hydrocarbons is allowable (about 25%) in either liquid or vapor, when the chlorinated product must be removed from the paraffin hydrocarbons by distillation. If these chlorinated hydrocarbons are not removed by distillation when the saturation equals about 25%, the addition of more chlorin leads to the formation of-dichlorids.

If, however, this maximum conversion is attained in the liquid and at the same time the vapors are being chlorinated to the allo wable maximum conversion, then the allowable total saturation of monochlor-hydrocarbons becomes larger before it is necessary members of the paraffin hydrocarbons hav-' ing more than one carbon atom'which consists in first. treating the liquid hydrocarbons in the liquid phase with chlorin, and then treating the vapors from the liquid phase chlorination in a separate reaction chamber with chlorin and in the vapor phase under pressure.

3. The process of chlorinating the lower members of the paraflin hydrocarbons h-aving more than one carbon atom which con- .sists in first treating the hydrocarbons in the liquid phase with chlorin, then treating the vapors from the liquid phase chlorination in a separate reaction chamber and in the vapor phase with chlorin in the presence of actinic light. a

4. The process of continuously chlorinating the lower members of the paraflin hydrocarbons having more than one carbon atom which consists in first treating the hydrocarbons in the liquid phase with chlorin, then treating the vapors from the liquid phase chlorination in a separate reaction chamber with chlorin, and in the vapor phase, and at the end of a complete unit or series of units returning the unconverted lower members of the paraflin hydrocarbons to the liquid phase chlorination unit.

In testimony whereof, I aflix'my signature.

HUGH T. BOYD. V 

